1. Field of the Invention
The present invention relates to a wireless communication terminal and communication method using wireless communication technology represented by cellular telephones and Personal Digital Assistants.
2. Description of the Related Art
Wireless communication systems incorporate various systems, for example, TDMA (Time Division Multiple Access), CDMA (Code Division Multiple Access), W-CDMA (a European version of Wideband CDMA), 1xEV-DO (1x Evolution-Data Optimized), PHS (Personal Handy phone Service), wireless LAN (Local Area Network), UWB (Ultra Wideband), infrared wireless, etc. Furthermore, cellular phone service incorporating a plurality of these wireless communication technologies is evolving at a phenomenal pace. In this case, it is necessary to communicate by selectively switching communication systems (communication modes) according to surrounding radio wave propagation conditions.
As a transmission retry method in cases where a plurality of these wireless communication systems are installed, a technique is known from conventional prior art which selectively switches a plurality of modulation circuits and varies the transmission retry count (synonymous in meaning to the number of times or frequency to retry transmission) of the radio wave (wireless communication electromagnetic wave) depending on the wireless transceiver rate for transmitting data. For example, the subject matter disclosed in Japanese Laid-Open (Kokai) Patent Application No. 2002-247133 titled “WIRELESS COMMUNICATION APPARATUS.”
Apart from that, during radio wave reception conditions influenced by noise, interference, attenuation, etc., a transmitted radio wave from a terminal has difficulty reaching a network and similarly a response from a network has difficulty reaching a terminal. In this case, after shifting to an idle state, a transmission operation is also performed prior to data transmission and reception. In the event there is no response from a network for a communication transmission because of poor radio wave conditions, transmission retries are executed in order to establish a line connection.
However, the technology disclosed in the above-mentioned conventional prior art reference with installed terminal modulation circuits consisting of different wireless transmission speeds is a technique for varying the transmission retry count relative to the transmission error rate after connection completion and restated corresponds to a selected wireless transmission speed (=communication system). Consequently, this technology does not vary the transmission retry count in a transmission operation performed prior to data transmission and reception. Therefore, the conventional prior art has a disadvantage because the transmission retry count at the time of a transmission operation is fixed. In an environment where radio wave reception conditions are under the influence of noise, interference, attenuation, etc., the process for establishing a connection requires a longer time interval (time period) and furthermore, since radio wave output continues, excessive electrical power is expended during this period.